Fiber reinforced composites are known in the art and described in U.S. Pat. Nos. 4,617,219; 4,366,255; 2,677,955; and 4,668,548.
Conventionally, cementitious composites are made by shipping the reinforcing fibers to the job site where the fibers are either directly mixed with the cement, mortar, or concrete and poured into a mold or the fibers are placed into a mold and infiltrated with a cement composition. Because, as explained in the reference patents, only about 2% by volume fiber can be incorporated into a cementitious composition when the fibers are mixed with the composition directly, the latter practice is preferred. To facilitate this practice, it is known to make the fibers into a mat and to place the mats into a mold. However, the practice remains undesirable because it is labor intensive and the amount of fiber used is difficult to control as it will depend on the degree to which the fibers are compacted, which can vary from worker to worker.
It is known to manufacture metal fiber in mats and to use these mats on the job site to make reinforced cementitious structures. In the methods described in the above patents, the fibers are in any desired size. The fibers may be formed into a continuous fiber mat by directing the fibers onto a conveyor belt apparatus. The fiber mat may be placed into a form or cavity and then infiltrated with a cementitious composition or it may be transported to the job site and deposited into a cavity, and then infiltrated with a cementitious composition.
In addition to being labor intensive, this also requires maintenance of a large fiber or fiber mat inventory at the job site. This invention limits the step of having the purchaser build a form which corresponds to a desired composite's shape and lay the fibers into the form to make a cementitious structure having the desired shape. With this invention, the purchaser need only enclose a fiber preform, which can be manufactured to contain a predetermined volume percentage fiber, in a mold and infiltrate the preform with cementitious composition. Furthermore, the fiber preform can have any predetermined dimension and shape. Instead of a mat having a thickness of 2 to 4 inches, the preform can take on any desired shape, for example, a column, a cube or even a ladle lip ring. A desired and more efficient manner now exists to fabricate a reinforced member that can be used with a cementitious composition.